*: support where in admin show ddl statement

[crazycs520]

What problem does this PR solve?

mysql>admin show ddl jobs where job_type='create table'
+--------+---------+------------+--------------+--------------+-----------+----------+-----------+-----------------------------------+-----------------------------------+--------+
| JOB_ID | DB_NAME | TABLE_NAME | JOB_TYPE     | SCHEMA_STATE | SCHEMA_ID | TABLE_ID | ROW_COUNT | START_TIME                        | END_TIME                          | STATE  |
+--------+---------+------------+--------------+--------------+-----------+----------+-----------+-----------------------------------+-----------------------------------+--------+
| 136    | test    | t          | create table | public       | 1         | 135      | 0         | 2019-09-29 17:41:40.561 +0800 CST | 2019-09-29 17:41:40.565 +0800 CST | synced |
+--------+---------+------------+--------------+--------------+-----------+----------+-----------+-----------------------------------+-----------------------------------+--------+

What is changed and how it works?

Check List

Tests

• Unit test

Code changes

• Has exported function/method change

Side effects

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to be included in the release note

[kennytm]

LGTM

[zimulala]

LGTM